The Advanced Access Content System (“AACS”) is a specification for protecting prerecorded and recordable media content stored on the next generation of optical media used for DVD (Digital Versatile Disc), including HD DVD™ and Blu-ray™. Such optical media are typically configured for consumer use with PCs (personal computers) and other consumer electronic devices that include high-definition media players. The AACS specification is maintained by AACS Licensing Administrator, LLC (“AACSLA”).
AACS provides several mechanisms to manage usage of stored media content which may include movies, games, television programming, and the like. Digital copying is securely prevented by the encoding of the content with a 128 bit AES (Advanced Encryption Standard) key-code. HD DVD and Blu-ray players use their own device key, from which they are able to calculate the correct AES key-code called a Media Key, for each disc through use of a Media Key Block (“MKB”), and typically Key Conversion Data (“KCD”), that are stored on the data-carrier (e.g., an optical disc). Use of the MKB enables AACS to implement a key revocation model by which device keys on specific players that have been compromised, for example through circumvention of the content protection, can be revoked.
In addition, the copy-protection methodology used by AACS supports some Digital Rights Management (“DRM”) functionality to provide users with the freedom to consume disc contents legally on other devices such as media-servers or portable equipment. The number and type of devices and the timeframe, in which they can be used, can be defined in the AACS system by the owner of the contents during the media authoring process.
While AACS is performing satisfactorily in many applications, some vulnerability to attack is believed to exist which could compromise the integrity of the protection for the media content. For example, if the base line content protection under AACS is broken, HD DVD and Blu-ray discs can be decrypted without authorization. Once attackers understand the process and secrets behind the AACS content protection methodology, they can write a program that automates the process to allow illegal decryption by users that have minimal technical skill.
As a result of such vulnerability, content providers have expressed interest in a form of content protection that can be applied on a per-title basis, which varies from title-to-title on a DVD disc in order to make it at least somewhat more difficult for an attacker to create an automated program for illegal decryption of the recorded content.
This Background is provided to introduce a brief context for the Summary and Detailed Description that follow. This Background is not intended to be an aid in determining the scope of the claimed subject matter nor be viewed as limiting the claimed subject matter to implementations that solve any or all of the disadvantages or problems presented above.